Preparation of malto-oligosaccharides

ABSTRACT

Disclosed is a method for preparing a mixture of malto-oligosaccharides. Generally, a dry-milled corn fraction, such as a corn flour from which germ and fiber have been removed, is subjected to hydrolysis, typically catalyzed with acid or an enzyme such as an α-amylase enzyme, under conditions suitable to form a mixture of malto-oligosaccharides. A gluten fraction is removed and the enzyme is inactivated, such as with heat. The mixture of malto-oligosaccharides then may be recovered from remaining solids and purified.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. Provisional Application No.61/787,067, filed Mar. 15, 2013, which is hereby incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to grain milling for purposes ofrecovering useful grain fractions.

BACKGROUND

Many oligosaccharides are commonly prepared by the control hydrolyticcleavage of starches. In the production of oligosaccharides, theglycosidic linkages of the starch molecules are partially hydrolyzed toyield at least one oligosaccharide species, and more typically, amixture of oligosaccharide species. The oligosaccharide mixtures soprepared typically include at least one malto-oligosaccharide species.Malto-oligosaccharides are characterized as having a saccharide backbonethat comprises predominantly 1-4 glycosidic linkages.

Malto-oligosaccharides may be characterized by their degree ofpolymerization (DP) which refers to the number of saccharide monomerunits in each molecule. Each malto-oligosaccharide species also may becharacterized by its dextrose equivalent value (DE) which is a measureof the reducing power of the malto-oligosaccharide relative to dextroseand which may be determined by the Lane and Eynon method or theLuff-Schoorl method as known in the art. Conventionalmalto-oligosaccharides generally are divided into maltodextrins andsyrup solids. Malto-oligosaccharides having a DE of less than 20 areknown as maltodextrins, whereas malto-oligosaccharides having a DE of 20or greater are known as syrup solids.

Malto-oligosaccharides generally may be prepared via the corn wetmilling process. In the corn wet milling process, corn is soaked insulfur dioxide (SO₂) for a typical period of roughly 24-36 hours. Thiscauses the corn kernel to separate into its four main component parts,which are germ, protein, fiber, and starch. The starch is then recoveredand, when used for the production of malto-oligosaccharides, issubjected to enzymatically catalyzed hydrolysis to yield a mixturemalto-oligosaccharides. The other component parts of the corn are usedas feed or are themselves further processed to yield other commerciallyvaluable products. The corn wet milling process is commerciallypracticed at present by Grain Processing Corporation of Muscatine, Iowa.Grain Processing Corporation is a commercial supplier of many food-grademalto-oligosaccharides sold under the MALTRIN® trademark. MALTRIN®malto-ologosaccharides are filtered, carbon-treated, and spray-driedproducts. The commercially available MALTRIN® product line covers arange of DE values from 5-25. Exemplary MALTRIN® products includeMALTRIN® M040; MALTRIN® M100; MALTRIN® M150; MALTRIN® M180, and MALTRIN®QD grades M500, M510, M550, and M580.

The corn wet milling process, while well established, makes use of asubstantial amount of sulfur dioxide. For some purposes it would bedesirable to provide a method for production of malto-oligosaccharidesthat is capable of practice using less sulfur dioxide.

SUMMARY

It has now been found that malto-oligosaccharides can be prepared fromdry-milled corn or other grain. Generally, a dry-milled corn fraction isprovided. The corn fraction may be, for example, a corn fraction fromwhich germ and fiber have been at least substantially removed. The cornfraction is then subjected to enzymatically catalyzed hydrolysis,preferably with an α-amylase enzyme, under conditions suitable to resultin a mixture of malto-oligosaccharides. In further processing, theenzyme then may be inactivated, such as with heat or by changing the pH,such as by adding acid. The mixture of malto-oligosaccharides having aDE of at most 70 then is recovered from remaining solids, such as bycentrifugation. Surprisingly, a malto-oligosaccharide mixture comparablein purity to conventionally prepared malto-oligosaccharides may beprepared in some embodiments. Optionally, the mixture may be furtherpurified, such as by filtration or treatment with activated carbon.Surprisingly, it has been found that the malto-oligosaccharides can havea protein content of less than 1% and an ash content of less than 2.5%.The method may be practiced in the substantial absence of sulfur dioxideand other sulfurous additives.

The method may but need not include the steps of dry milling corn toform a corn product and preparing a fraction from the corn product, suchas by separating germ and fiber to result in a corn fraction from whichat least substantially all of said germ and fiber had been removed.

In other embodiments, not mutually exclusive with respect to the above,the invention encompasses a product prepared by providing a cornfraction, such as a fraction from which germ and fiber have been atleast substantially removed, the corn fraction having been prepared froma dry-milled corn product; subjecting said corn fraction toenzymatically catalyzed hydrolysis under conditions suitable to resultin a mixture of malto-oligosaccharides, and terminating the hydrolysisto form a mixture of malto-oligosaccharides having a DE of at most 70.This product is itself valuable as an intermediate in the preparation ofmore purified malto-ologosaccharides.

The method may be practiced using sulfur dioxide in certain steps, butin many embodiments may be practiced using less sulfur dioxide per unitweight of corn than the conventional wet milling process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart that generally represents steps in one embodimentof the process described herein.

FIG. 2 is a flow chart that generally representing steps in aconventional wet milling process used for ethanol production.

FIG. 3 is a flow chart representing generally steps in a dry millingprocess for ethanol production.

FIG. 4 is a flow chart representing generally steps in a “quick germ”dry grind process.

FIG. 5 is a flow chart generally representing steps in a process forpreparing maltodextrin from starch in a conventional corn wet millingprocess

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The remainder of the description herein will be specified with respectto corn, but it should be understood that the subject matter describedherein is equally applicable to other starch-bearing grains, such aswheat, rice, potato, and tapioca. Any suitable corn may be used inconnection with the invention, for instance, yellow dent corn.

Generally, the disclosed embodiments pertain to the production ofmalto-oligosaccharides, or mixtures of predominantly 1-4 linked glucosylunits. In many embodiments, at least 50% of the saccharide units in themalto-oligosaccharide prepared in accordance with the present teachingsare linked via 1-4 linkages; in many embodiments, at least 55%; in manyembodiments at least 60%; in many embodiments at least 65%; in manyembodiments at least 70%; in many embodiments at least 75%; in manyembodiments at least 80%; in many embodiments at least 85%; in manyembodiments at least 90%; and in many embodiments at least 95% of thesaccharide units in the malto-oligosaccharide are linked via 1-4linkages. Malto-oligosaccharides are contemplated to include saccharidesspecies that have an odd DP value and in many cases the mixture ofmalto-oligosaccharides will include some dextrose (DP 1). Themalto-oligosaccharides may have a DE of any conventional value, andthus, for instance, the DE of the mixture of malto-oligosaccharides maybe 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21,22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39,40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, or 70. In someembodiments the DE of the mixture of malto-oligosaccharides may rangefrom 3-25 and in some embodiments from 5-25. In some embodiments themixture is a maltodextrin and in other embodiments the mixture is asyrup or syrup solid. In other embodiments the DE is less than 50. Forinstance, the mixture of malto-oligosaccharides may have a DE of lessthan 49, less than 48, less than 47, less than 46, less than 45, lessthan 44, less than 43, less than 42, less than 41, less than 40, lessthan 39, less than 38, less than 37, less than 36, less than 35, lessthan 34, less than 33, less than 32, less than 31, less than 30, lessthan 29, less than 28, less than 27, less than 26, less than 25, lessthan 24, less than 23, less than 22, less than 21, less than 20, lessthan 19, less than 18, less than 17, less than 16, less than 15, lessthan 14, less than 13, less than 12, less than 11, less than 10, lessthan 9, less than 8, less than 7, less than 6, less than 5, less than 4,or less than 3.

Further details concerning maltodextrins and applications formaltodextrins can be found in U.S. Pat. No. 7,728,125 “Reducedmalto-oligosaccharides”; U.S. Pat. No. 7,595,393 “Reducedmalto-oligosaccharides”; U.S. Pat. No. 7,405,293 “Reducedmalto-oligosaccharides”; U.S. Pat. No. 7,265,078 “Drilling fluidapparatus and method”; U.S. Pat. No. 7,091,335 “Derivatized reducedmalto-oligosaccharides”; U.S. Pat. No. 6,946,148 “Method for absorbingfluid”; U.S. Pat. No. 6,919,446 “Reduced malto-oligosaccharides”; U.S.Pat. No. 6,828,310 “Compositions including reduced malto-oligosaccharidepreserving agents, and methods for preserving a material”; U.S. Pat. No.6,806,231 “Drilling fluid, apparatus, and method”; U.S. Pat. No.6,720,418 “Derivatized reduced malto-oligosaccharides”; U.S. Pat. No.6,613,898 “Reduced malto-oligosaccharides”; U.S. Pat. No. 6,610,672“Compositions including reduced malto-oligosaccharide preserving agents,and methods for preserving a material”; U.S. Pat. No. 6,593,469“Compositions including reduced malto-oligosaccharide preservingagents”; U.S. Pat. No. 6,528,629 “Malto-oligosaccharide derivedglycosides”; U.S. Pat. No. 6,518,223 “Drilling fluid, apparatus, andmethod”; U.S. Pat. No. 6,475,979 “Reduced malto-oligosaccharidecleansing compositions”; U.S. Pat. No. 6,436,678 “High purity maltoseprocess and products”; U.S. Pat. No. 6,391,293 “Lanthionizingcompositions, systems, and methods”; U.S. Pat. No. 6,380,379“Derivatized reduced malto-oligosaccharides”; and U.S. Pat. No.6,375,798 “Derivatized malto-oligosaccharides, methods for trashscavenging, and process for preparing a paper web”; all assigned toGrain Processing Corporation of Muscatine, Iowa.

Generally, the invention contemplates preparation of amalto-oligosaccharide mixture from a dry-milled corn fraction. “Dry”does not connote the complete absence of moisture, and to the contraryit is understood that the corn will contain some moisture as isnaturally present and/or as is introduced to remove from the corn duringconventional shipping, handling, and storage. It is contemplated in someembodiments that dry-milled corn itself is subjected to enzymaticallycatalyzed hydrolysis. In many embodiments, however, it is a fraction ofthe corn that is subjected to enzymatically catalyze hydrolysis. Forexample, the corn fraction may be a dry-milled corn fraction from whichcorn germ has been removed. In other embodiments, the dry-milled cornfraction can be a fraction from which fiber has been removed. In manycases, the dry-milled corn fraction can be a fraction from which bothgerm and fiber had been removed. By “removed” in this context iscontemplated the least substantial removal of the indicated componentsvia conventional or otherwise suitable techniques. For example, theremoval of fiber is described in Singh et al., “Recovery of Fiber in theCorn Dry-grind Ethanol Process: A Feed Stock for Valuable Coproducts,”Cereal Chem. 76 (6:868-72) (1999) and removal of germ is described inSingh et al., “Effect of Corn Oil on Stillage Evaporators,” Cereal Chem.76 (6:846-49) (1999).

For comparison to known processes, with reference now to FIG. 1, onegeneralized process 10 is shown. At step 12, dry corn is provided. Thecorn is de-germed and fiber is removed, as shown in steps 14 and 16respectively, to form a flour from which germ and fiber are removed. Theinvention is not limited to practice using such a flour, and it iscontemplated that other corn fractions may be employed. In theillustrated embodiment, the resulting flour contains both starch andcorn gluten. To this fraction in step 18 is added an enzyme, generallyan α-amylase enzyme, and the temperature is brought to any temperaturesuitable for allowing the enzyme to be operative to catalyze thehydrolysis of the starches in the corn fraction. In some embodiments,the temperature is 100-200° F.; in the illustrated embodiment, thetemperature is 107° F. Any suitable enzyme may be employed and it iscontemplated that the temperature may be brought to an optimal operatingtemperature for the enzyme. The enzyme may be added in any amountrelative to the solids weight; for example, 0.02-0.4% of the solidsweight.

In accordance with the exemplary process shown in FIG. 2, as shown instep 20, liquefaction is allowed to proceed until the desired DE isattained. Those of skilled in the art will recognize that the exactamount of time of necessity will vary depending on factors such astemperature and enzyme, but it is believed that a period of time rangingfrom 5 to 50 hours; in some embodiments 24-36 hours, may be sufficientin many cases to yield a mixture of malto-oligosaccharides within adesired range of DE values. At step 22, the enzyme is inactivated,generally by elevating the temperatures sufficient to neutralize theenzyme.

The resulting fraction is a crude fraction that comprisesmalto-oligosaccharides in an aqueous mixture. Via subsequent steps, asshown in step 24, the malto-oligosaccharides may be separated fromgluten and other remaining solids in the mixture. As shown at step 26,the malto-oligosaccharides may be subjected to purification steps suchas filtration and carbon treatment. Subsequently or prior thereto, themixture may be dried, such as by drum or spray drying.

The protein content of the corn fraction is typically greater than 5%,some of which is soluble protein in the wet milling process.Surprisingly, it has been found that the malto-oligosaccharides preparedin accordance with the teachings described herein can have a proteincontent of less than 1%. Some of the protein originally present in thecorn is ordinarily soluble when the corn is processed using the wetmilling process to form malto-oligosaccharides, and it was unexpectedlyfound that the protein content of the malto-oligosaccharides producedupon centrifugation, where the soluble malto-oligosaccharides areseparated from other components, contained a lower-than-expected amountof protein.

In some embodiments, the protein content is less than 0.9%; in someembodiments, less than 0.8%; in some embodiments, less than 0.7%; insome embodiments, less than 0.6%; in some embodiments, less than 0.5% bydry solids weight. Similarly, the malto-oligosaccharides prepared inaccordance with the teachings described herein can have an ash contentof less than 2.5%; in some embodiments, less than 2.4%; in someembodiments, less than 2.3%; in some embodiments, less than 2.2%; insome embodiments, less than 2.1%; in some embodiments, less than 2.0%;in some embodiments, less than 1.9%; in some embodiments, less than1.8%; in some embodiments, less than 1.7%; in some embodiments, lessthan 1.6%; in some embodiments, less than 1.5%; in some embodiments,less than 1.4%; in some embodiments, less than 1.3%; in someembodiments, less than 1.2%; in some embodiments, less than 1.1%; insome embodiments, less than 1.0%; in some embodiments, less than 0.9%;in some embodiments, less than 0.8%; in some embodiments, less than0.7%; in some embodiments, less than 0.6%; in some embodiments, lessthan 0.5% by dry solids weight.

The above process has been demonstrated with respect to enzymaticallycatalyzed hydrolysis, but it should be understood that the invention isnot limited thereto. Any suitable process for hydrolyzing starch toyield malto-oligosaccharides can be employed. In some embodiments, thehydrolysis is catalyzed with mineral or other acids, such as citric orother food grade acids, and in some embodiments, the hydrolysis iscatalyzed with an acid and one or more enzymes. In some cases an acidand an enzyme can be employed sequentially in either order as may beappropriate.

By comparison to the conventional wet milling process shown in FIG. 2,corn is provided, and is steeped at step 28 using sulfur dioxide tocause the corn to separate into its four major components. As shown at30, the steep water is removed, and the corn proceeds to grinding atstep 32 and de-germination at step 34. Fine grinding and sieving occurat steps 36 and 38 respectively, with fiber removal at step 40. Theresulting product is centrifuged at step 42 and gluten is removed at 44,thus yielding starch. The starch is then saccharified at step 46,typically to dextrose. The dextrose is then fermented and distilled toform ethanol, as shown in steps 48 and 50 respectively.

Alternatively, as shown in FIG. 5, the starch may be liquefied viapartial saccharification at step 52 using enzymatically catalyzedhydrolysis to form malto-oligosaccharides. In FIG. 5, corn is provided,and is steeped at step 28′ using sulfur dioxide to cause the corn toseparate into its four major components. As shown at 30′, the steepwater is removed, and the corn proceeds to grinding at step 32′ andde-germination at step 34′. Fine grinding and sieving occur at steps 36′and 38′ respectively, with fiber removal at step 40′. The resultingproduct is centrifuged at step 42′ and gluten is removed at 44′, thusyielding starch. FIGS. 2 and 5 are idealized flow charts and in practicevarious modifications will be apparent to those of skill in the art.

With respect to the ethanol production process from dry milling as shownin FIG. 3, corn is ground, as shown in step 54, and is then mash cookedat step 56. The resulting mixture is saccharified at step 58, and theproduct is fermented at step 60 and distilled at step 62, typically to aeutectic mixture of ethanol and water. Besides ethanol, the resultingproduct is known as distillers dried grains with solubles (“DDGS”).

Singh, V. and others (see Singh et al. “Comparison of Modified Dry-grindCorn Processes for Fermentation Characteristics and DDGS Composition,”Cereal Chem. 82 (2):187-190 (2005) and Singh et al., “Recovery of Fiberin the Corn Dry-grind Ethanol Process: A Feedstock for ValuableCoproducts,” Cereal Chem. 82 (76):868-72 (1999)) have proposed processedterm “quick germ” and “quick germ quick fiber.” Briefly, and asdescribed in Wahjudi et al., “Quick Fiber Process Effect of MashTemperature, Dry Solids, and Residual Germ on Fiber Yield and Purity,”Cereal Chem. 77 (5):640-44 (2000), as shown in FIG. 4, corn is ground atstep 64, and at steps 66 and 68, germ and fiber are removedrespectively. The remaining product is mash cooked at step 70, andsaccharified at step 72. The resulting product is then treated much asin the conventional starch process, with the starch being fermented todextrose at step 74 and the ethanol thus form distilled at step 76 toyield eutectic ethanol and DDGS.

The following Examples are provided to illustrate certain embodiments ofthe disclosed invention but should not be construed as limiting thescope of the invention.

EXAMPLES Example 1

De-germinated corn flour having the following chemical analysis wasprovided:

Fat (%, dsb) 0.8 Ash (%, dsb) 0.4 Protein (%, dsb) 5.2 Moisture (%) 8.7Starch (%, dsb) 82.5

The corn flour was slurried in water at 25% solids. Then, ValleyResearch Ultra Thin 100 L enzyme (as-is solution) was added to the cornflour slurry at a rate 0.1% wt. based on solids weight. The slurry wasthen cooked using a steam jet cooker with temperature setting at around220° F. for 10 minutes. The cooked starch was held in containers for 90to 120 minutes at 195 to 200° F. to allow the enzyme to hydrolyze thestarch. Samples were taken to measure DE of the starch hydrolysates.When a targeted DE was achieved, solution of citric acid (50% w/w)solution was added to the slurry to bring its pH to 4.0 to 4.2. Then thestarch hydrolysate slurry was cooked in a jet cooker at 210° F. to 220°F. to inactivate the enzyme. The enzyme inactivated hydrolysate was thencentrifuged on a Sharples P660 decanter centrifuge to remove insolublesolids. Activated carbon like SA-1500 from MeadWestvaco Corporation, inan amount of 1.5% weight of starch hydrolysate solid weight, was thenmixed into the centrifuged hydrolysate slurry. The slurry was held at185° F. for 30 min with mixing. Then the slurry was filtered using arotary filter with Celatom Diatomaceous Earth FW 40 pre-coat filter aidto remove insoluble materials. The filtrate was then collected andspray-dried.

The slurry was analyzed before centrifugation and found to have thefollowing analysis:

Slurry before centrifuge Test Result Moisture (%) 84.3 Solids (%) 15.7DE 16.9 Protein (%, dsb) 8.7

The centrifuge liquid was found to have the following chemical analysis:

Liquid from Centrifuge Test Result Moisture (%) 83.8 Solids (%) 16.2 DE14.9 Protein (%, dsb) 1.4

Example 2

The de-germinated corn flour used in Example 1 was slurried in water at25% solids. Then, DSM Veritase enzyme (as-is solution) was added to thecorn flour slurry at a rate 0.1% wt. based on solids weight. The slurrywas then cooked using a steam jet cooker with temperature setting ataround 220° F. for 10 minutes. The cooked starch was held in containersfor 90 to 120 minutes at 195 to 200° F. to allow the enzyme to hydrolyzethe starch. Samples were taken to measure DE of the starch hydrolysates.When a targeted DE was achieved, solution of citric acid (50% w/w)solution was added to the slurry to bring its pH to 4.0 to 4.2. Then thestarch hydrolysate slurry was cooked in a jet cooker at 210° F. to 220°F. to inactivate the enzyme. The enzyme inactivated hydrolysate was thencentrifuged on a Flottweg Z23-3/441 decanter centrifuge to removeinsoluble solids. Activated carbon like SA-1500 from MeadWestvacoCorporation, in an amount of 1.5% weight of starch hydrolysate solidweight, was then mixed into the centrifuged hydrolysate slurry. Theslurry was held at 185° F. for 30 min with mixing. Then the slurry wasfiltered using a rotary filter with Celatom Diatomaceous Earth FW 40pre-coat filter aid to remove remaining insoluble matters. The filtratewas then collected and spray-dried.

The slurry was analyzed and found to have the following chemicalanalysis:

Slurry before centrifuge Test Result Moisture (%) 81.0 Solids (%) 19.0DE 12.2 Protein (%, dsb) 1.6

In addition, the liquid from the centrifuge and the finished productafter drying were analyzed and found to have the following analyses.

Liquid from Centrifuge Test Result Moisture (%) 82.2 Solids (%) 17.8 DE22.1 Protein (%, dsb) 0.4

Finished product Test Result Moisture (%) 3.4 Ash (%, dsb) 0.7 Protein(%, dsb) 0.3 DE 23.3

The maltodextrin prepared in accordance with this Example wassurprisingly pure, with protein and ash content each below 1%. It isbelieved that the increase in DE as between the centrifuge liquid andthe dried product may be due to retention of large malto-oligosaccharidespecies on the filter during the purification step.

Example 3

The de-germinated corn flour used in Example 1 was slurried in water at25% solids. Then, DSM Veritase enzyme (as-is solution) was added to thecorn flour slurry at a rate 0.1% wt. based on solids weight. The slurrywas then cooked using a steam jet cooker with temperature setting ataround 220° F. for 8 minutes. The cooked starch was then heated toaround 280° F. for 2 minutes to deactivate the enzyme. Then, the slurrywas cooled to around 210° F. and Validase BAA 1500 L enzyme was added tothe cooked slurry at a rate of 0.1% wt based on solids weight. Thecooked starch was held in containers for 180 to 240 minutes at 195 to200° F. to allow the enzyme to hydrolyze the starch. Samples were takento measure DE of the starch hydrolysates. When a targeted DE wasachieved, solution of citric acid (50% w/w) solution was added to theslurry to bring its pH to 4.0 to 4.2. Then the starch hydrolysate slurrywas cooked in a jet cooker at 210° F. to 220° F. to inactivate theenzyme. The enzyme inactivated hydrolysate was then centrifuged on aFlottweg Z23-3/441 decanter centrifuge to remove insoluble solids. Thecentrifuged slurry was then filtered in a Graver Technologiesmicrofilter with a pore size of 0.1 micron. The filtered hydrolysate wasthen treated by passing through a bed of PAD900 adsorbent resin fromPurolite. The treated solution was then collected and spray-dried. Theproducts produced had a DE range from 3 to 25. The slurry beforecentrifugation and the centrifuge mud and liquid were evaluated andfound to have the following chemical analyses:

Slurry Before Centrifuge Moisture (%) 78.7 Solids (%) 21.3 DE 13 Protein(%, dsb) 4.1

Centrifuge Mud Moisture (%) 67.8 Fat (%, dsb) 1.1 Ash (%, dsb) 0.9Protein (%, dsb) 14.4 Starch (%, dsb) 57.4

Liquid from Centrifuge Moisture (%) 78.1 DE 11.4 Protein (%, dsb) 2.5

A product having a DE of 14.4 was evaluated and found to have thefollowing chemical analysis:

Finished Product Moisture (%) 3.8 Ash (%) dsb 0.4 Protein (%) as is 0.3DE 14.4

The maltodextrin prepared in accordance with this Example wassurprisingly pure, with protein and ash content each below 0.5%.

Example 4

The de-germinated corn flour used in Example 1 was slurried in water at25% solids. Then, HCl was added to the corn flour slurry to adjust theconductivity to 1200 to 1600 μS/cm. The slurry was then cooked using asteam jet cooker with temperature setting at around 265° F. for 10minutes. Then, the slurry was cooled to around 210° F. and a slurry ofsoda ash (diluted to 5 baume) was added to the hydrolysate to adjust thepH to 6.4 to 6.8 and Validase BAA 1500 L enzyme was added to the cookedslurry at a rate of 0.02% wt. based on solids weight. The cooked starchwas held in containers for 180 to 240 minutes at 195 to 200° F. to allowthe enzyme to hydrolyze the starch. Samples were taken to measure DE ofthe starch hydrolysates. When a targeted DE was achieved, solution ofHCl was added to the slurry to bring its pH to 4.0 to 4.2. Then thestarch hydrolysate slurry was cooked in a jet cooker at 210° F. to 220°F. to inactivate the enzyme. The enzyme inactivated hydrolysate was thencentrifuged on a Flottweg Z23-3/441 decanter centrifuge to removeinsoluble solids. The centrifuged slurry was then filtered in a GraverTechnologies microfilter with a pore size of 0.1 micron. The filteredhydrolysate was then treated by passing through a bed of PAD900adsorbent resin from Purolite. The treated solution was then collectedand spray-dried.

The slurry before centrifugation, centrifuge mud, and liquid from thecentrifuge were analyzed and found to have the following chemicalanalyses:

Slurry before centrifuge Test Result Moisture (%) 84.7 Solids (%) 15.3DE 17.2 Protein (%, dsb) 5.9

Centrifuge Mud Test Result Moisture (%) 66.1 Fat (%, dsb) 0 Ash (%, dsb)0.6 Protein (%, dsb) 13.8 Starch (%, dsb) 63.1

Liquid from Centrifuge Test Result Moisture (%) 84.8 Solids (%) 15.2 DE19.4 Protein (%, dsb) 3.9

Example 5

A de-germinated corn flour having the following chemical analysis wasprovided:

Fat (%, dsb) 1.4 Ash (%, dsb) 0.7 Protein (%, dsb) 5.8 Moisture (%) 12.3Starch (%, dsb) 83.6

The de-germinated corn flour was slurried in water at 25% solids. Then,HCl was added to the corn flour slurry to adjust the conductivity to1200 to 1600 μS/cm. The slurry was then cooked using a steam jet cookerwith temperature setting at around 265° F. for 10 minutes. Then, theslurry was cooled to around 210° F. and a slurry of soda ash (diluted to5 baume) was added to the hydrolysate to adjust the pH to 6.4 to 6.8 andValidase BAA 1500 L enzyme was added to the cooked slurry at a rate of0.02% wt. based on solids weight. The cooked starch was held incontainers for 180 to 240 minutes at 195 to 200° F. to allow the enzymeto hydrolyze the starch. Samples were taken to measure DE of the starchhydrolysates. When a targeted DE was achieved, solution of HCl was addedto the slurry to bring its pH to 4.0 to 4.2. Then the starch hydrolysateslurry was cooked in a jet cooker at 210° F. to 220° F. to inactivatethe enzyme. The enzyme inactivated hydrolysate was then centrifuged on aFlottweg Z23-3/441 decanter centrifuge to remove insoluble solids.Activated carbon like SA-1500 from MeadWestvaco Corporation, 1.5% weightof starch hydrolysate solid weight, was then mixed into the centrifugedhydrolysate slurry. The slurry was held at 185° F. for 30 min withmixing. Then the slurry was filtered using a rotary filter with CelatomDiatomaceous Earth FW 40 pre-coat filter aid to remove remaininginsoluble matters. The filtrate was then collected and spray-dried.

The slurry before centrifugation and the centrifuge mud and liquid wereevaluated and found to have the following chemical analyses:

Slurry Before Centrifuge Moisture (%) 83.1 Solids (%) 16.9 DE-Osmometer14.7 Protein (%, dsb) 5.3

Centrifuge Mud Moisture (%) 70.8 Fat (%, dsb) 0.2 Ash (%, dsb) 0.7Protein (%, dsb) 12.5 Starch (%, dsb) 62.3

Liquid from Centrifuge Moisture (%) 81.8 Solids (%) 18.2 DE-Osmometer15.1 Protein (%, dsb) 2.0

The spray-dried maltodextrin was evaluated and found to have thefollowing chemical analysis:

Moisture (%) 4.1 Ash (%) dsb 2.1 Protein (%) as is 0.4 DE (Schoorl) 13.9

The maltodextrin prepared in accordance with this Example wassurprisingly pure, with protein content below 0.5%.

It is thus seen that a method for preparation of malto-oligosaccharidesand malto-oligosaccharide product are provided.

Except as otherwise clearly indicated by context, all weight percentagesexpressed herein are on a dry solids basis.

All references cited herein are hereby incorporated by reference intheir entireties.

Uses of singular terms such as “a,” “an,” are intended to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The terms “comprising,” “having,” “including,”and “containing” are to be construed as open-ended terms. Anydescription of certain embodiments as “preferred” embodiments, and otherrecitation of embodiments, features, or ranges as being preferred, orsuggestion that such are preferred, is not deemed to be limiting. Theinvention is deemed to encompass embodiments that are presently deemedto be less preferred and that may be described herein as such. Allmethods described herein can be performed in any suitable order unlessotherwise indicated herein or otherwise clearly contradicted by context.The use of any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended to illuminate the invention and does notpose a limitation on the scope of the invention. Any statement herein asto the nature or benefits of the invention or of the preferredembodiments is not intended to be limiting. This invention includes allmodifications and equivalents of the subject matter recited herein aspermitted by applicable law. Moreover, any combination of theabove-described elements in all possible variations thereof isencompassed by the invention unless otherwise indicated herein orotherwise clearly contradicted by context. The description herein of anyreference or patent, even if identified as “prior,” is not intended toconstitute a concession that such reference or patent is available asprior art against the present invention. No unclaimed language should bedeemed to limit the invention in scope. Any statements or suggestionsherein that certain features constitute a component of the claimedinvention are not intended to be limiting unless reflected in theappended claims. Neither the marking of the patent number on any productnor the identification of the patent number in connection with anyservice should be deemed a representation that all embodiments describedherein are incorporated into such product or service.

What is claimed is:
 1. A method of preparing malto-oligosaccharides,said method comprising: providing a corn fraction, said corn fractionhaving been prepared from a dry-milled corn flour from which germ andfiber have been at least substantially removed; subjecting said cornflour to hydrolysis under conditions suitable to result in a mixture ofmalto-oligosaccharides; and recovering said mixture ofmalto-oligosaccharides, the mixture recovered having a dextroseequivalent value (DE) of at most 70 and a protein content of less than1%.
 2. A method according to claim 1, said corn fraction beingcatalytically hydrolyzed with an enzyme.
 3. A method according to claim2, said enzyme comprising an α-amylase enzyme.
 4. A method according toclaim 2, further comprising inactivating said enzyme with heat.
 5. Amethod according to claim 2, further comprising inactivating said enzymewith acid.
 6. A method according to claim 1, further comprisingseparating said malto-oligosaccharide mixture from a mixture ofremaining solids.
 7. A method according to claim 6, further comprisingpurifying said malto-oligosaccharide mixture.
 8. A method according toclaim 7, said mixture of malto-oligosaccharides having an ash content ofless than 1%.
 9. A method according to claim 7, said purificationcomprising treatment with activated carbon.
 10. A method according toclaim 1, further comprising separating germ and fiber from a dry-milledcorn product to form said corn fraction.
 11. A method according to claim10, further comprising dry milling corn to form said dry-milled cornproduct.
 12. A method of preparing malto-oligosaccharides, said methodcomprising: dry milling corn to form a corn product: separating germ andfiber to result in a corn flour from which at least substantially all ofsaid germ and fiber had been removed; subjecting said corn flour toenzymatically catalyzed hydrolysis using an α-amylase enzyme underconditions suitable to result in a mixture of malto-oligosaccharides;inactivating said α-amylase enzyme; recovering saidmalto-oligosaccharide mixture from said mixture of remaining solids,said malto-oligosaccharide mixture having a DE of at most 70 and aprotein content of less than 1%; and purifying saidmalto-oligosaccharide mixture.
 13. The method of claim 1, saidhydrolysis being conducted in a jet cooker.
 14. The method of claim 7,said hydrolysis being conducted in a jet cooker.
 15. The method of claim12, said hydrolysis being conducted in a jet cooker.
 16. The method ofclaim 1, said recovery including a centrifugation step to separatemalto-oligosaccharides from insoluble materials.
 17. The method of claim7, said recovery including a centrifugation step to separatemalto-oligosaccharides from insoluble materials.
 18. The method of claim12, said recovery including a centrifugation step to separatemalto-oligosaccharides from insoluble materials.
 19. The method of claim1, further comprising spray-drying the resulting malto-oligosaccharides.20. The method of claim 7, further comprising spray-drying the resultingmalto-oligosaccharides.
 21. The method of claim 12, further comprisingspray-drying the resulting malto-oligosaccharides.
 22. The method ofclaim 13, further comprising spray-drying the resultingmalto-oligosaccharides.
 23. The method of claim 14, further comprisingspray-drying the resulting malto-oligosaccharides.
 24. The method ofclaim 15, further comprising spray-drying the resultingmalto-oligosaccharides.